Temporal Features of Muscle Synergies in Sit-to-Stand Motion Reflect the Motor Impairment of Post-Stroke Patients

Ningjia Yang, Qi An, Hiroki Kogami, Hiroshi Yamakawa, Yusuke Tamura, Kouji Takahashi, Makoto Kinomoto, Hiroshi Yamasaki, Matti Itkonen, Fady Shibata-Alnajjar, Shingo Shimoda, Noriaki Hattori, Takanori Fujii, Hironori Otomune, Ichiro Miyai, Atsushi Yamashita, Hajime Asama

Research output: Contribution to journalArticlepeer-review

38 Citations (Scopus)


Sit-to-stand (STS) motion is an important daily activity, and many post-stroke patients have difficulty performing STS motion. Previous studies found that there are four muscle synergies (synchronized muscle activations) in the STS motion of healthy adults. However, for post-stroke patients, it is unclear whether muscle synergies change and which features primarily reflect motor impairment. Here, we use a machine learning method to demonstrate that temporal features in two muscle synergies that contribute to hip rising and balance maintenance motion reflect the motor impairment of post-stroke patients. Analyzing the muscle synergies of age-matched healthy elderly people ( $n = 12$ ) and post-stroke patients ( $n = 33$ ), we found that the same four muscle synergies could account for the muscle activity of post-stroke patients. Also, we were able to distinguish post-stroke patients from healthy people on the basis of the temporal features of these muscle synergies. Furthermore, these temporal features were found to correlate with motor impairment of post-stroke patients. We conclude that post-stroke patients can still utilize the same number of muscle synergies as healthy people, but the temporal structure of muscle synergies changes as a result of motor impairment. This could lead to a new rehabilitation strategy for post-stroke patients that focuses on activation timing of muscle synergies.

Original languageEnglish
Article number8823953
Pages (from-to)2118-2127
Number of pages10
JournalIEEE Transactions on Neural Systems and Rehabilitation Engineering
Issue number10
Publication statusPublished - Oct 2019
Externally publishedYes


  • Muscle synergy
  • post-stroke
  • random forest
  • rehabilitation
  • sit-to-stand

ASJC Scopus subject areas

  • Internal Medicine
  • General Neuroscience
  • Biomedical Engineering
  • Rehabilitation


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